An agricultural combine is a large machine used to harvest a variety of crops from a field. During a harvesting operation, a header at the front of the combine cuts ripened crop from the field. A feederhouse supporting the header transfers the crop material into the combine. Threshing and separating assemblies within the combine remove grain from the crop material and transfer the clean grain to a grain tank for temporary holding. Crop material other than grain exits from the rear of the combine. An unloading auger transfers the clean grain from the grain tank to a truck or grain cart for transport, or to another receiving bin for holding.
Draper headers are header types commonly used when harvesting crops such as small grains, peas, lentils, and rice. Such draper headers comprise a cutter bar and two or more conveying transversely moving belts arranged in a forward direction behind the cutter bar that convey the cut crop towards the center of the header, where it is fed towards the rear by another conveyor belt assembly that feeds the crop towards a rear outlet of the header and to a feederhouse of the combine. During a harvesting operation with this header type, it is desirable to maintain a cutting height as low as possible to the ground in order to collect substantially the entire ripe crop from the field. To accomplish this, combines typically employ a header float system or a terrain following system to enable the header to follow the ground over changing terrain without gouging or digging into the soil.
U.S. Pat. Nos. 3,717,995, 3,623,304, and 4,724,661 disclose examples of header float systems using resilient structures to suspend the header, thereby reducing the apparent weight of the header, allowing it to lightly skid across the ground over changing terrain. U.S. Pat. Nos. 3,597,907, 4,622,803 and 5,471,823 disclose examples of similar float systems, but using dynamic structures to suspend the header. U.S. Pat. Nos. 5,577,373, 6,041,583 and 6,758,029 B2 disclose examples of terrain following systems using dynamic structures to position the header, thereby sensing and changing the vertical position of the header to follow changing terrain.
Such float systems allow for independent movement of rollers supporting the belt in a vertical direction, such that they can follow the ground contours closely. As a result, problems occur in guiding the belt properly over the roller, since both rollers at the two ends of the belt may move by different distances and even in different directions.
Published patent application US 2005/022491 describes a platform header for a combine with a rigid frame, a cutter bar and three belts arranged side by side for conveying the crop rearward to a transverse auger. The belts comprise at their lateral ends inwardly extending wedges neighboring the side walls of the deflection rollers, in order to prevent the belt from running off the rollers. Published patent application US 2006/254241 A describes a similar platform header in which cover plates between adjacent belts are located in lower positions as the lateral end of the belt, in order to prevent crop or residues from entering between the cover and the belt.
What is needed in the art is a draper header with belts conveying the crop in a transverse direction, allowing appropriate guidance of the belts also when rollers independently move in a vertical direction.